Many household products are dispensed from pressurized containers through a dispensing valve, which containers are generally referred to as “aerosol containers.” Conventional aerosol containers are usually pressurized by a volatile liquid propellant, which provides an adequate pressure for dispensing even after a portion of the product has been dispensed from the container.
When filling conventional aerosol products, a manufacturer fills a can with the product and promptly charges it with the volatile propellant. The filled can, in a ready-to-use form, is then shipped according to U.S. Department of Transportation rules. For example, container designs given a DOT-2Q designation must be rated to withstand 270 psi and container designs given a DOT-2P designation must be rated to withstand 240 psi.
Conventional aerosol containers may be configured such that, for example, the product and propellant are in contact, or the product is housed in a bag within the can while the propellant is housed outside the bag, or a piston separates the product from the propellant. An example of the latter is EarthSafe™ Dispensing Technology, marketed by Crown Cork and Seal.
A type of popular, conventional aerosol can structure is referred to as a three piece can, in which the parts are (i) a can “body” formed by rolling a flat sheet and welding the vertical seam, (ii) a “bottom” attached to the body by a seam, and (iii) an “end” seamed onto the top of the body. The end is dome-shaped. A flange for seaming to the can body is formed at the bottom of the aerosol end. A curl for receiving a valve is formed at the top of the aerosol end. Prior art aerosol cans include steel ends on steel bodies, aluminum ends on aluminum bodies, and aluminum ends on steel bodies.
Another conventional aerosol can includes an integral bottom and body formed in a process referred to as impact extrusion, such as sold by Exal Corporation. The impact extrusion process rams a slug of aluminum into the can body shape. Impact extrusion forms a relatively thick base. Shaped cans are also in the marketplace. Also, some aerosol containers have an integral can bottom and sidewall, as the body is formed by drawing and ironing.
Regardless of the structure of the can body, a dome on an aerosol can is ubiquitous in commercial aerosol containers. As illustrated in FIG. 1, a typical prior art container 110 includes a can body 112 that is seamed onto a dome 114. A valve cup 116 is crimped into the dome 114 by the filler at curl 124. The product is filled either before fitting the cup or through the valve 118. The mass of the top component (that is, the dome) and valve cup is large because of the raised structure and need for the crimp to form a gas tight seal at pressures of up to 18 bar pressure. Sidewall 112 and dome 114 are connected at seam 120. As illustrated in FIG. 1, the upper end of the stem 128 of valve 118, the upper end of the body 132, and the upper end of the ferrule 126 are above the uppermost point of the seam 120. FIG. 2 illustrates container 110 without valve cup 116 and valve 118.